Greatly disturbed over husband showing sluggishness (8)
I believe the answer is:
lethargy
'sluggishness' is the definition.
(I know that sluggishness can be written as lethargy)
'greatly disturbed over husband' is the wordplay.
'disturbed' is an anagram indicator (the order of letters is disturbed).
'over' means one lot of letters goes inside another.
'husband' becomes 'h'.
'greatly' is an anagram of 'letargy'.
'letargy' going around 'h' is 'LETHARGY'.
'showing' acts as a link.
(Other definitions for lethargy that I've seen before include "Drowsy" , "Extreme lack of energy, listlessness" , "Lassitude, languor" , "Lack of vitality or energy" , "Unnatural drowsiness" .)